BAGHDAD, Jan. 1 -- Iraq's most productive oil refinery reopened Saturday after closing for 10 days under the threat of insurgent attacks, a move that might ease a fuel crisis that has worsened long lines of anxious buyers at gas stations across the country. But the battle over the linchpin of Iraq's economy -- its enormous oil supply -- is far from over.

A police official in Kirkuk said Iraqi and U.S. forces had killed a Kurdish demonstrator who was part of a rally in the city demanding free kerosene and gasoline. The protesters set fire to two gas stations in the city. Also, a bomb exploded at an oil pipeline near a refinery in Baghdad, the Associated Press reported.

The Baiji refinery in northern Iraq reopened after police began escorting delivery trucks from the refinery, roughly 150 miles north of Baghdad, to gas stations all over the country, Ahmed Ibrahim, the distribution manager of the refinery, said in an interview.

The refinery had closed in December after insurgents threatened to kill drivers making deliveries of gasoline to gas stations around the country. Assem Jihad, an Oil Ministry spokesman, said last week that the shutdown was costing $20 million a day. Ibrahim said that the refinery, fully stocked with gasoline it could not ship out, was being forced to burn its supply of crude oil because trucks from Turkey and Jordan could not take it away.

The shutdown was suffocating the country's supply of gasoline and led to long gas lines. Though Iraq is estimated to have the world's third-largest oil reserves, it imports gasoline because its oil-industry infrastructure has deteriorated so badly following years of fighting and economic stagnation.

Insurgent threats and attacks on oil pipelines, delivery trucks and gas stations have picked up since the government's recent decision to increase gasoline prices sharply. The move, demanded by Western governments as a condition of forgiving Iraq's debts, has been deeply unpopular among residents used to Iraq's traditionally low, heavily subsidized gasoline prices.

The protest in the Rahim Awa neighborhood of Kirkuk, in an oil-rich part of northern Iraq, appeared to have been sparked by the price hikes. The demonstration was initially permitted by the authorities but soon spun out of control as arguments and fistfights broke out across the neighborhood, police Gen. Sarhad Abdul Qadir said in an interview.

The police fired a volley of warning shots and the crowd began attacking police cars and breaking windows. Police called for help from U.S. troops to break up the riot. Qadir said that five civilians were wounded in the clashes, one of whom later died. Police imposed a curfew in the city starting at 6 p.m., Qadir said.

Insurgents detonated 14 car bombs across the country Sunday, eight of them in the capital, according to reports from the Associated Press and a police spokesman. Two Iraqi civilians were killed in a car bomb attack against a convoy of U.S. troops in Baiji, said Capt. Hakeem Muhammed, an Iraqi police spokesman.

The remaining attacks killed no one, according to the Associated Press.

In a raid involving helicopter-borne troops of the 101st Airborne Division, forces detained a high-ranking former Baath Party member and suspected insurgent financier in northern Iraq as well as his three sons, a U.S. military spokesman and an Iraqi police officer said.

Accounts of the raid on Hay Sufon, a village near the town of Hawija, about 30 miles southwest of Kirkuk, did not agree on details. Lt. Col. Fattah Abdullah, of the Hawija police, said in an interview that the operation took place Sunday morning and was conducted by the Americans. In an e-mailed statement, Lt. Col. Edward Loomis, a U.S. military spokesman, said that it happened Saturday afternoon and was led by the Iraqi army, supported by American troops.

Abdullah identified the detainee as Atiya Shindakh, a former Baath official in the northeastern, predominantly Kurdish region of Iraq. Loomis would not identify the detainee.

In Baghdad, a Sudanese official said that insurgents had released six kidnapped members of its embassy's staff after Sudan announced it would close the embassy as the kidnappers had demanded, the Associated Press reported.

The AP also reported that gunmen had killed the 17-year-old son of a Palestinian diplomatic attache Saturday. Insurgents have repeatedly attacked Arab diplomats from countries that have opened embassies in Iraq in what is described as an effort to keep foreign governments from having relations with the Iraqi government.

Special correspondents Naseer Nouri and Omar Fekeiki in Baghdad and Salih Saif Aldin in Baiji contributed to this report.